Paper Technology International 2024 - Journal - Page 142
PAPERTECHNOLOGYINTERNATIONAL
MC pumping,
MMedium-consistency
chemical mixing, and tower
management systems in the
newest pulp mills
Jussi Heinonen, Product Manager MC Equipment
Reijo Vesala, Head of Business Segment, Pulp, Paper, and Board
Janne Tamminen, Pump Performance Expert Sulzer Pumps Finland Oy
INTRODUCTION:
Pumping of liquids with a high dry solids content and mixing of bleaching chemicals are matters of great importance for the pulp and
paper industry. The proven MCE pumps from Sulzer achieve a previously unattained level of performance when it comes to the capacity
range, temperature, and pressure of the pumped medium. They cover a wide range of different pumping system applications for new lines
and upgrades of old lines.
Mixing chemicals and stock is one of the most important
operations in stock bleaching. Good mixing provides homogenous
bleaching conditions, reduces the consumption of chemicals and
energy, improves product quality, and reduces the environmental
load. The manufacture of pulp and paper entails the pumping
and mixing of stock and other suspensions in numerous process
stages as well as through many reactors and towers. Sulzer
supplies medium-consistency MC pumps, SX chemical mixers, MC
discharge scrapers for towers and big reactors, MC dischargers,
and SALOMIX tower management systems (TMS) with agitators.
They represent the most important stock transfer process equipment
in modern oxygen deligni昀椀cation and bleaching processes.
Figure 1: A typical O2 deligni昀椀cation and bleaching process in
a chemical pulp mill. Sulzer produces equipment that ful昀椀lls
all pumping and mixing requirements and enhances process
ef昀椀ciency by facilitating stable and reliable operation through
reactors and towers.
Developments over time
The 昀椀rst commercial 昀氀uidizing centrifugal mediumconsistency MC pump with degassing started in a chemical pulp
bleaching application in 1980. The 昀椀rst-generation MC pumps
were brought into the market in the 1980’s, followed by the second
generation in the early 1990’s. The innovative third-generation MCE
pumps are now running in several pulp and paper mills around
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the world, and in most of the high-capacity, single-line bleaching
processes.
The highest capacities for the MC pumps can be up to
10’000 air dry metric tons per day (admt/d). Over the years, Sulzer
has introduced several improvements to the MC pumping system
products, such as larger capacity ranges, higher pump heads, higher
pumping consistencies and lower energy consumption.
MC pumping and chemical mixing systems are the
most important stock transfer equipment in the modern oxygen
deligni昀椀cation and bleaching processes in recycled 昀椀ber and
mechanical pulp lines. Besides MC pumps, there is a great number
of other process equipment and solutions where the principles of
MC technology have been applied. These include the SX chemical
mixers for mixing both gaseous and liquid bleaching chemicals and
steam into the pulp,
the MC discharge scraper for discharging high-consistency
towers, and the 昀氀uidizing MC discharger for effective 昀氀ow splitting
and up-昀氀ow tower feed and discharge. Ef昀椀cient ‘in- line’ dilution
systems for diluting MC pulp with the static DM dilution mixer
into lower consistency enable an improvement of the existing
applications.
Innovative Sulzer MCE pump series – a new level of MC
performance with MCE pumps
A new level of MC performance over a wide consistency,
temperature and pressure range is provided by the unique Fluider™
impeller, comprising effective multifunctional turbulence generation,
gas separation, pumping hydraulics, and degassing combined
with a wide passage gas removal system of high capacity. These
guarantee that the ideal high-performance MC pump is available for
the prevailing pumping conditions and applications, offering optimum
reliability and interchangeability with the existing earlier- generation
MC pumps.
The MCE pump is provided with a separate external MDS
degassing system or with a built-in degassing system. The new
technology also makes it possible to arrange several MC pumping
applications without installing any degassing pumps and without
additional components, extra controls, or drive motors. Sulzer uses
the Fluider™ technology and specially designed impellers for pumps
developed for intermediate (SEMI-MC) and medium-consistency
(MC) applications. The Fluider™ technology uses twisted 昀氀uidizer
